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I Assembly 
of the second quarry. It continues to bound the limestone on the west 
until it finally disappears below the red sandstone formation near Capt. 
DeCamp's, two miles west of Grassy Point. It is a continuation of 
the bed of talcose slate described in Westchester and Putnam counties, 
as ranging from Blue-Rock Point, at the mouth of Peekskill creek, 
through Gallows Hill, and so on into Putnam county. It is adapted 
for use as a fine stone for the in-walls of furnaces, but is applied to 
no use at present. 
At the junction of this rock with the limestone at the south end of 
the Tompkins upper quarry, the rock is loaded with carbon and pyrites. 
The slate is glazed with films of anthracite, and was supposed to be 
anthracite coal. Statements were made in the papers of the discovery 
of a coal mine, and the owner is stated to have been offered $5,000 for 
it but refused, in consequence of its supposed value. 
Hornblende, Serpentine and Augite Rocks. 
Hornblende rock forms the west part of Stony Point. It is inter- 
mixed with serpentine rock in some places, and in others it contains 
grains of magnetic oxide of iron. Diggings have been made here in 
search of iron ore, but no quantity of it has been found. Trap dykes 
cut through these rocks, and even penetrate the granite east of it, but 
not in such a way as to injure that rock for quarrying. Augite rocks 
occur in many places in Rockland and Orange counties, but it is not 
applied to any use. Black serpentine rock occurs near Forshee's mine 
in Orange county: it resembles that of Brown's quarry in Putnam 
county. 
Limestone. 
This rock occurs abundantly in Orange and Rockland counties. Those 
of Orange are highly important on account of their economical applica- 
tions, and of much interest in consequence of the great number of beau- 
tifully crystallized and rare minerals that they contain. They are de- 
scribed in the descriptive geology of Orange county by Dr. Horton, in 
the appendix to this report. 
The primary limestone of Rockland is not very extensive, but, from 
its location, it is of high economical importance. It skirts the shore of 
the Hudson for a mile or more, from the landing on the cove at the 
northwest point of Stony Point to a little north of Tompkins' most 
northern quarry. It extends thence to near Capt. De Camp's, two miles 
west of Grassy Point, where it disappears beneath the red sandstone 
